The present invention is directed to mechanism for a molded case circuit breaker capable of switching a rotary contact structure between on, off and tripped positions.
The present invention is directed to a molded case circuit breaker having a mechanism for switching a rotary contact system between on, off and tripped positions.
U.S. Pat. No. 5,281,776 (""776) describes a molded case circuit breaker having a toggle type mechanism for switching a rotary contact system. This mechanism utilizes a lower linkage that directly attaches to a drive shaft which extends through and rotates the contact system, as is shown in FIG. 1. A crank attached to the same drive pin is used to drive another pin that also extends through the contact system. Since the drive shaft passes through the contact system, optimum positioning of this shaft may not be possible which may cause geometric constraints on how much force can be transferred from the switching mechanism to the rotor. This often limits the performance level that a circuit breaker which uses the ""776 switching mechanism is able to achieve.
Therefore, it is desirable to optimize the switching mechanism to transmit an increased amount of force to a rotary contact system.
It is also considered desirable in conjunction with the improved switching mechanism to describe an interface between the mechanism and the contact system that allows for flexibility in the placement and design of the mechanism.
In accordance with the present invention a circuit breaker mechanism is provided that comprises a side frame having a cradle attached thereto. A toggle linkage consisting an upper link having a first and second end attaches to the cradle and a lower link attached to the upper link second end by a spring spindle. A crank member attached to the side frame attaches to the lower link. The crank provides the output torque generated by the mechanism.
Also in accordance with the present invention, a first and second shaft extend through a rotor assembly. The first shaft connects with the crank to drive the rotor assembly between a closed and open position in response to a change in state of the circuit breaker mechanism.